/Engine/Source/Runtime/GeometryCore/Public/Spatial/BlockedDenseGrid3.h
Call an external lambda with a reference to the grid value at CellIJK. Called as Func(ElemType&), so the caller can both read and write the grid cell
template<typename ProcessFunc> void ProcessValueThreadSafe ( const [FVector3i](API\Runtime\GeometryCore\FVector3i) & CellIJK, ProcessFunc Func )